8.5 Forecasts
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1310 – Revised Joint IMO/IHO/WMO Manual on Maritime Safety Information (MSI) – (8 June 2009) - Annex - 8 – Meteorological Warnings and Forecasts - 8.5 Forecasts

8.5 Forecasts

  8.5.1 The forecasts given in part III of weather and sea bulletins shall have the following content and order of items:

  • .1 the valid period of forecast;

  • .2 name or designation of forecast area(s) within the main MSI area; and

  • .3 a description of:

    • (i) wind speed or force and direction;

    • (ii) sea state (significant wave height/total sea);

    • (iii) visibility when forecast is less than five nautical miles; and

    • (iv) ice accretion, where applicable.

  8.5.2 The forecasts should include expected significant changes during the forecast period, significant meteors such as freezing precipitation, snowfall or rainfall, and an outlook for a period beyond 24 hours. In addition, phenomena such as breaking seas, cross seas, and abnormal waves should also be included, where possible.

  8.5.3 The valid period should be indicated either in terms of number of hours from the time of issue of the forecast or in terms of dates and time in UTC of the beginning and the end of the period.

  8.5.4 The following descriptive terms should be used for visibility:

  • (i) very poor (less than 0.5 nautical miles)

  • (ii) poor (0.5 to 2 nautical miles)

  • (iii) moderate (2 to 5 nautical miles)

  • (iv) good (greater than 5 nautical miles)

Parent topic: 8 – Meteorological Warnings and Forecasts
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